The formation of ice in aircraft fuel is an unavoidable problem because in warmer climates water becomes entrained in the fuel where it does not present a problem when the temperature is above freezing point, but when the temperature drops below the freezing point the entrained water may form ice crystals which can block fuel filters in aircraft fuel systems, particularly at high fuel flow rates such as during aircraft take-off. It is known to provide a bypass valve in an aircraft fuel supply system such that when the fuel filter is blocked by ice formation, the bypass valve can be actuated to allow fuel to bypass the fuel filter and flow directly to, for example a fuel regulator. Various efforts to improve such fuel filter and bypass valve arrangements have been and continue to be made in order to overcome associated problems such as limited transient icing capability, relatively bulky and heavy configurations, etc.
Therefore, there is a need for an improved fuel filter and bypass valve for aircraft gas turbine engines.